The present invention relates to a composition for a bottom anti-reflective coating material, which is effective in reducing the adverse effect of the reflection from the background substrate in the lithography process using various radiations, and to a method for forming a resist pattern using this composition for a bottom anti-reflective coating material.
A photoresist is coated on a substrate such as semiconductor wafer, glass, ceramic or metal to have a thickness of from 0.5 to 2 xcexcm by a spin coating method or a roller coating method and thereafter subjected to heating, drying, printing of a circuit pattern through an exposure mask with radiation such as ultraviolet ray, post exposure baking if desired, and development to form an image.
This image as a mask is etched so as to effect pattern working on the substrate. Representative examples of the application field thereof include the production process of semiconductors such as IC, the production of circuit substrates such as liquid crystal and thermal head and other photofabrication process.
In the semiconductor fine working using a photoresist, accompanying the tendency towards finer dimensions, a matter of great importance is the prevention of light reflection from the substrate. For this purpose, a photoresist containing a light absorbent has been conventionally used, however, the use has a problem that the resolution is impaired. Accordingly, a method of providing a bottom anti-reflective coating (BARC) between the photoresist and the substrate has been broadly investigated. Known examples of the bottom anti-reflective coating are an inorganic coating type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon and xcex1-silicon, and an organic coating type comprising a light absorbent and a polymer material. The former requires equipments such as a vacuum evaporation apparatus, a CVD apparatus and a sputtering apparatus, for the coating formation. The latter does not require any particular equipment advantageously and a large number of studies are being made thereon. For example, JP-B-7-69611 (the term xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese patent publicationxe2x80x9d) describes a coating comprising a condensate of a diphenylamine derivative with a formaldehyde-modified melamine resin, an alkali-soluble resin and a light absorbent, U.S. Pat. No. 5,294,680 describes a reaction product of a maleic anhydride copolymer with a diamine-type light absorbent, JP-A-6-118631 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) describes a coating comprising a resin binder and a methylolmelamine-base heat cross-linking agent, JP-A-6-118656 describes an acrylic resin-type anti-reflective coating containing within the same molecule a carboxylic acid group, an epoxy group and a light absorbing group, JP-A-8-87115 describes a coating comprising methylolmelamine and a benzophenone-base light absorbent, and JP-A-8-179509 describes a coating obtained by adding a low molecular light absorbent to a polyvinyl alcohol resin.
The material for organic bottom anti-reflective coating preferably has physical properties such that it exhibits a large absorbance to radiations, it is insoluble in the photoresist solvent (not to cause intermixing with the photoresist layer), it is free from dispersion of a low molecular substance from the anti-reflective coating material to the overcoat photoresist layer during the coating or drying by heating, and it has a high dry etching rate as compared with the photoresist. These are also described, for example, in Proc. SPIE, Vol. 2195, 225-229 (1994).
However, the compounds described in the above-described patent publications fail to satisfy all these requirements and improvements have been demanded. For example, some conventional bottom anti-reflective coatings are insufficient in the light absorbing power of the binder and require separate loading of a light absorbent, and some contain a large amount of an aromatic light absorbent for increasing the absorbance but has a problem that the dry etching rate is low. Further, those having, in the cross-linking system, a functional group capable of increasing the alkali permeability such as a carboxylic acid group, are bound to a problem that when development with an alkaline aqueous solution is performed, the anti-reflective coating swells to incur the worsening of the resist pattern shape.
An object of the present invention is to provide a composition for a bottom anti-reflective coating material, which has large light absorbance, can form excellent resist pattern-with high resolution and low film thickness dependency, and shows high dry etching rate.
Another object of the present invention is to provide a method for forming a resist pattern, which is high in the dry etching rate and can form an excellent resist pattern having excellent light absorbance with high resolution and low film thickness dependency.
Still another object of the present invention is to provide a photoresist bottom anti-reflective coating material composition having high effect of preventing reflective light of the exposure light (particularly, light at a wavelength of 248 nm) on the photoresist, substantially free of intermixing with the photoresist layer, causing no dispersion into the photoresist layer on drying by heating, having a high dry etching rate as compared with the photoresist, and capable of forming a resist pattern with high resolution and low film thickness dependency.
Still further object of the present invention is to provide a method for forming a resist pattern, which has high effect of preventing reflective light of the exposure light (particularly, light at a wavelength of 248 nm) on the photoresist, is substantially free of intermixing with the photoresist layer, causes no dispersion into the photoresist layer on drying by heating, has a high dry etching rate as compared with the photoresist, and can form a resist pattern with high resolution and low film thickness dependency.
These objects of the present invention can be attained by the following constructions:
(1) a composition for a bottom anti-reflective coating material, comprising a polymer compound having a structure represented by the following formula (I) or (II) on the side chain: 
wherein W represents a linking group to the polymer main chain, Y represents an oxygen atom, a sulfur atom or xe2x95x90Nxe2x80x94V, Z1 and Z2, which may be the same or different, each represents an electron donating group, m and n represent an integer of from 0 to 2 and from 0 to 3, respectively, and when m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different, and V represents xe2x80x94OH, xe2x80x94NH2, a linear, branched or cyclic alkyl group having from 1 to 20 carbon atoms, wherein the alkyl group may have a substituent, an aromatic or heterocyclic or heteroaromatic ring group having from 5 to 14 carbon atoms, which may have a substituent, or an alkoxy group having from 1 to 20 carbon atoms;
(2) a composition for a bottom anti-reflective coating material, comprising a polymer compound having a structure represented by the following formula (III) or (IV) as a part of the repeating unit on the main or side chain: 
wherein Y represents an oxygen atom, a sulfur atom or xe2x95x90Nxe2x80x94V, Z1 and Z2, which may be the same or different, each represents an electron donating group, m and n represent an integer of from 0 to 2 and from 0 to 3, respectively, and when m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different, and V represents xe2x80x94OH, xe2x80x94NH2, a linear, branched or cyclic alkyl group having from 1 to 20 carbon atoms wherein the alkyl group may have a substituent, an aromatic or heteroaromatic ring group having from 5 to 14 carbon atoms, which may have a substituent, or an alkoxy group having from 1 to 20 carbon atoms;
(3) a composition for a bottom anti-reflective coating material, comprising a polymer compound having a repeating unit of the structure represented by formula (V) or (VI): 
wherein R1 represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom or a cyano group, X represents a divalent linking group, Y, Z1, Z2, m and n have the same meanings as defined in item (1), and when m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different;
(4) a composition for a bottom anti-reflective coating material as described in item (3), wherein in formula (V) or (VI), Z1 and Z2 each is a group selected from xe2x80x94OH, xe2x80x94OR4, xe2x80x94NR5R6 and xe2x80x94SR4 wherein R4 represents a hydrocarbon group having from 1 to 20 carbon atoms, and R5 and R6, which may be the same or different, each represents a hydrogen atom or a hydrocarbon group having from 1 to 20 carbon atoms;
(5) a composition for a bottom anti-reflective coating material, comprising the following components (a) and (b):
(a) a polymer compound having a structure represented by formula (I) or (II) described in item (1); and
(b) a melamine, guanamine, glycoluril or urea compound substituted by at least one substituent selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group;
(6) a composition for a bottom anti-reflective coating material as described in item (5), wherein in formula (I) or (II), W is a single bond or a linking group containing a group selected from an alkylene group which may have a substituent, an arylene group which may have a substituent and an aralkylene group which may have a substituent wherein W may have one or more of xe2x80x94CO2xe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94 and xe2x80x94SO2xe2x80x94 in the middle thereof, and Z1 and Z2 each is a group selected from xe2x80x94OH, xe2x80x94OR4, xe2x80x94SR4 and xe2x80x94NR5R6 wherein R4 represents a hydrocarbon group having from 1 to 20 carbon atoms, and R5 and R6, which may be the same or different, each represents a hydrogen atom or a hydrocarbon group having from 1 to 20 carbon atoms, and when m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different;
(7) a composition for a bottom anti-reflective coating material comprising the following components (a) and (c):
(a) a polymer compound having a structure represented by formula (I) or (II) described in item (1); and
(c) a phenol, naphthol or hydroxyanthracene compound substituted by two or more groups selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group;
(8) A composition for a bottom anti-reflective coating material as described in item (7), wherein in formula (I) or (II), W is a single bond or a linking group containing a group selected from an alkylene group which may have a substituent, an arylene group which may have a substituent and an aralkylene group which may have a substituent wherein W may have one or more of xe2x80x94CO2xe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94 and xe2x80x94SO2xe2x80x94 in the middle thereof, and Z1 and Z2 each is a group selected from xe2x80x94OH, xe2x80x94OR4, xe2x80x94SR4 and xe2x80x94NR5R6 wherein R4 represents a hydrocarbon group having from 1 to 20 carbon atoms, and R5 and R6, which may be the same or different, each represents a hydrogen atom or a hydrocarbon group having from 1 to 20 carbon atoms, and when m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different;
(9) a composition for a bottom anti-reflective coating material as described in item (1), wherein the polymer compound having a structure represented by formula (I) or (II) contains from 2 to 50 wt % of a repeating structural unit represented by the following formula (VII): 
wherein R2 represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom or a cyano group, and A represents an organic functional group having a xe2x80x94CH2OH, xe2x80x94CH2OR4 or xe2x80x94CH2OCOCH3 terminal group wherein R4 represents a hydrocarbon group having from 1 to 20 carbon atoms;
(10) a composition for a bottom anti-reflective coating material as described in item (9), wherein A in formula (VII) is a group resulting from the reaction of xe2x80x94CONHCH2OH, xe2x80x94CONHCH2OCH3, xe2x80x94C6H4CH2OH, xe2x80x94C6H4CH2OCH3 or xe2x80x94CONHC(CH3)2CHCOCH3 with formalin;
(11) a composition for a bottom anti-reflective coating material as described in item (1), wherein the polymer compound having a structure represented by formula (I) or (II) contains from 2 to 30 wt % of a repeating structural unit represented by the following formula (VIII): 
wherein R2 has the same meaning as R2 in item (9), and B represents an organic functional group having an epoxy terminal group;
(12) a bottom anti-reflective coating material composition comprising a polymer light absorbent having at least one group represented by the following formula (IX), (X), (XI), (XII), (XIII), (XIV) or (XV) on the side chain: 
wherein Wxe2x80x2 represents a divalent linking group, X1 to X3, which may be the same or different, each represents a hydrogen atom, a halogen atom, a cyano group or xe2x80x94(X4)pxe2x80x94R wherein R represents an alkyl group having from 1 to 20 carbon atoms, an aryl group having from 6 to 20 carbon toms or an aralkyl group having from 7 to 20 carbon atoms, which may have a substituent, X4 represents a single bond, xe2x80x94CO2xe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94, an alkylene group having from 2 to 4 carbon atoms or xe2x80x94SO2xe2x80x94, p represents an integer of from 1 to 10, Z1 and Z2, which may be the same or different, each represents an electron donating group, m and n represent an integer of from 0 to 2 and from 0 to 3, respectively, and when m is 2 or m and n each is 2 or 3, the Z1 groups or the Z2 groups may be the same or different, A1 represents a divalent aromatic ring or heteroaromatic ring group having from 5 to 14 carbon atoms, which may have a substituent, and A2 represents an aromatic ring or heteroaromatic ring group having from 5 to 14 carbon atoms, which may have a substituent;
(13) a bottom anti-reflective coating material composition comprising a polymer light absorbent having at least one structure represented by the following formula (XVI), (XVII), (XVIII), (XIX), (XX), (XXI), (XXII) or (XXIII) as at least a part of the repeating unit on the main or side chain: 
wherein X1 to X3, Z1, Z2, A1, A2, n and m each has the same meaning as defined in item (12);
(14) a bottom anti-reflective coating material composition comprising a polymer light absorbent having at least one repeating structural unit represented by the following formula (XXIV), (XXV) or (XXVI): 
wherein R1 represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom or a cyano group, Yxe2x80x2 represents a divalent linking group, X1, X2, Z1, Z2, m, n and A1 each has the same meaning as in item (12);
(15) a bottom anti-reflective coating material composition as described in item (14), wherein Yxe2x80x2 is a single bond, an alkylene, arylene or aralkylene group which may partially have one or more of xe2x80x94CO2xe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94COxe2x80x94 and xe2x80x94SO2xe2x80x94, or a group represented by xe2x80x94CO2xe2x80x94Exe2x80x94, xe2x80x94CONHxe2x80x94Exe2x80x94, xe2x80x94Oxe2x80x94Exe2x80x94, xe2x80x94COxe2x80x94Exe2x80x94 or xe2x80x94SO2xe2x80x94Exe2x80x94group wherein E represents a single bond or an aromatic ring group having from 6 to 14 carbon atoms, which may have a substituent;
(16) a bottom anti-reflective coating material composition as described in any one of items (12) to (15), wherein Z1 and Z2, which may be the same or different, each represents xe2x80x94OH, xe2x80x94OR4, xe2x80x94NR5R6 or xe2x80x94SR4 wherein R4 represents a hydrocarbon group having from 1 to 20 carbon atoms, and R5 and R6 each represents a hydrogen atom or a hydrocarbon group having from 1 to 20 carbon atoms;
(17) a bottom anti-reflective coating material composition as described in any one of items (12) to (16), wherein A1 and A2 each represents a divalent or monovalent group of benzene, naphthalene, anthracene, phenanthrene or thiophene ring, which may have a substituent;
(18) a bottom anti-reflective coating material composition as described in any one of items (12) to (17), wherein said polymer light absorbent contains from 2 to 50 wt % of the repeating structural unit represented by the following formula (XXVII): 
wherein R2 represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom or a cyano group, and B1 represents an organic functional group having xe2x80x94CH2OH, xe2x80x94CH2OR7 or xe2x80x94CH2OCOCH3 at the terminal wherein R7 represents a hydrocarbon group having from 1 to 20 carbon atoms;
(19) a bottom anti-reflective coating material composition as described in any one of items (12) to (17), wherein said polymer light-absorbent contains from 2 to 50 wt % of a repeating structural unit represented by formula (XXVII) of item (18) where B1 is a group obtained by the reaction of a group represented by xe2x80x94CONHCH2OH, xe2x80x94CONHCH2OCH3, xe2x80x94CH2OCOCH3, xe2x80x94C6H4(OH)CH2OH, xe2x80x94C6H4(OH)CH2OCH3 or xe2x80x94CONHC(CH3)2CH2COCH3, with formalin;
(20) a bottom anti-reflective coating material composition as described in any one of items (12) to (17), wherein said polymer light absorbent contains from 2 to 30 wt % of a repeating structural unit represented by the following formula (XXVIII): 
wherein R2 represents a hydrogen atom, a methyl group, a chlorine atom, a bromine atom or a cyano group, and B2 represents an organic functional group having an epoxy terminal group;
(21) a bottom anti-reflective coating material composition comprising the following components (a) and (b):
(a) a polymer light absorbent described in any one of items (12) to (20); and
(b) a melamine, guanamine, glycoluril or urea compound substituted by at least one substituent selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group;
(22) a bottom anti-reflective coating material composition comprising the following components (a) and (c):
(a) a polymer light absorbent described in any one of items (12) to (20); and
(c) a phenol, naphthol or hydroxyanthracene compound substituted by at least one substituent selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group; and
(23) a method for forming a resist pattern, which uses a bottom anti-reflective coating material composition described in any one of items (2) to (22).